Thanks in advance to all who reply!!
I upgraded from a C2D E6750 to a C2Q 9550 and used an after market HSF. I started a new project and want to reuse the C2D. I was going to use the C2Q stock fan but noticed the fins were smaller by 3/4 of an inch, along with the copper in the middle by 3/4 in dia. Also the C2D HSF has a plate connected to the push pins which in my eyes creates more cooling for the copper.
Sitting on the fan the C2Q fan sit 3/4 tall. The C2D is almost 2 1/2 in tall. Both fan are the same size both are 12VDC and both are0.60A.
This will go into a server so I want to turn it on and forget it.
The C2D fan would probably be better suited do it its larger size, that HSF was designed around a 65nm chip and the Q9550 is a 45nm chip (makes less heat). I have cooler designed for a E6550 (65nm) on an E7500 (45nm) and I can run it at 4.07Ghz stable @ 70 C (which is high but for a stock HSF its pretty good)